Here are the 10 latest developments in this story:
The CPM team that was made up of IT experts returned satisfied. The NCP's interest in the Election Commission's voting machines stemmed from its impression that the same machines were used to conduct this year's civic body polls in Maharashtra that it believes were rigged.
The election body clarified to them this wasn't the case. The NCP was, however, unhappy that they would be given access to only one of the 14 randomly selected machines and on their way out, called the exercise an "eye wash".
The Election Commission has written to the NCP to respond to its points. It turned out that the commission wasn't going to let parties check four machines, but only one. The others were on standby. Mr Zaidi said he left the door open for the NCP to come back to examine the vote machines on a later date, "either as an academic exercise or a challenge".
The Nationalist Congress Party and the CPM - the only parties to apply for the challenge - were given a demo of the EVMs and the VVPAT or voter-verifiable paper audit trail-equipped machines, which produce a paper receipt of the voter's choice for proof. The Election Commission has vowed to only use EVMs with this paper trail for all future elections.
Mr Zaidi said the controversy around tamperability of EVM after today's challenge and 100 % introduction of VVPAT is a "closed" chapter.
AAP, which has been most aggressive in alleging EVM tampering, chose not to participate in the Election Commission's challenge, calling it a fake exercise in which participants were not allowed to access the machine.
"The Election Commission challenge has flopped," said AAP's Saurabh Bhardwaj, who had held a demonstration in the Delhi Assembly with an EVM prototype.
AAP had announced its own parallel hackathon with prototypes of the EVM, asserting that it wants to prove the machines can be gamed. It invited parties, people and even Chief Election Commissioner Nasim Zaidi to take a shot.
To the EVM's sharpest critics, Mr Zaidi pointed to Friday's verdict of the Uttarakhand High Court that restrained everyone from "criticising use of EVMs in the recently conducted assembly elections". He said the commission would decide on the action to be taken if anything in this context was brought to its notice.
But Mr Kejriwal's party said it was only launching registrations today for the hackathon to be held on a different day and there was "confusion" among those who thought otherwise. They denied that they had changed their plans because of a perceived lack of response to their invite.